This application relates primarily to medical procedures which comprise entering the patient's body with an instrument to remove, ablate, extract, aspirate, modify, or repair tissue and fluids; to perform diagnostic procedures; or to deliver therapeutic agents or devices. The application also relates to implanted devices and to non-medical devices.
Some medical procedures are minimally invasive; such procedures can improve outcomes, speed recovery, limit trauma, and allow earlier intervention. Cannulas and related devices such as needles, catheters, and endoscopes are commonly used in such procedures, allowing surgical tools (including powered tools such as microdebriders driven by rotating flexible shafts), diagnostic and therapeutic instruments, implants, and drugs to be introduced into the body and excised tissue and fluid to be removed. Yet due to obstructions such as bone or sensitive organs, current devices may be unable to access a target region, or only do so sub-optimally. A more invasive method, a riskier approach, or a worse outcome is thus sometimes unavoidable. Moreover, in a number of procedures for which multiple targeted regions within the body need to be accessed, it can be time-consuming and involve multiple punctures or incisions, even if access to a single region would be straightforward. These issues arise from the fact that many instruments are substantially rigid and straight and follow substantially straight paths within the body, whether within a hollow (i.e., gas- or liquid-filled) organ or lumen, or in solid tissue. Moreover, even instruments known to the art that are not rigid and/or not straight can also have difficulty in accessing certain regions of the body, as the following examples will illustrate.
There has been extensive research into steerable needles, cannulas, catheters, and endoscopes; snake-like robots; and other devices. To date such devices have been problematic and many remain experimental. Spinning steerable needles with asymmetric tips [1, 2, 3, 4] offer small gauge sizes but have very large curvature/outer diameter (O.D.) ratios (e.g., 70:1 [5]), can only be deployed within solid tissue, and are difficult to control accurately due to varying tissue properties [6], etc. Concentric multi-tube superelastic nickel-titanium (Nitinol) needles [7, 8, 9, 10, 11] intended mostly for hollow regions offer relatively few shapes due to the small number of tubes; relatively large curvature/O.D. ratios [12]; limited stiffness; and small lumen/outside diameter ratios. Steerable catheters [13] and jointed, shape locking devices [14] have few degrees of freedom and sometimes large diameters. Snake-like robots [15, 16, 17] capable of following 3-D paths are typically 0.4-0.8″ diameter and use costly components; their lumen or inner diameter (I.D)/O.D. ratios also tend to be small. Finally, everting endoscopes [18] grow distally and are flexible but not steerable.
Given the limitations of instruments known to the art, there is a need for new, more capable and dexterous instruments capable of curved motion along desirable paths within the body, either within hollow (e.g., gas- or liquid-filled) regions or through solid tissue. Such instruments would preferably be deliverable with minimal difficulty and tissue trauma or damage and have a small outside diameter (e.g., 1-5 mm). They could provide a unique platform technology with the potential to impact a wide variety of medical specialties and procedures, including sinus and skull base surgery (where narrow passages and nearby critical structures make minimally invasive procedures difficult or impossible with current straight or angled instruments, e.g. in the frontal sinus, anterior cranial fossa, cavernous sinus, and brainstem), urology (where, for example, repeated access to specific regions of the kidney can be difficult), and interventional radiology (e.g., for biopsy and drainage while avoiding critical structures, and local regional therapy). Moreover, there is a need (e.g., for cochlear electrodes and annuloplasty rings) for implantable devices that can be delivered in a minimally invasive manner and which have complex 3-D curved shapes; this capability is currently very limited and could be greatly expanded by using the approaches of some embodiments of the invention.